The present invention relates to a method of salvaging stator cores. More specifically, this invention relates to a method of stripping magnet wire from stator cores having wedge, slot inner or wire insulation which is of a hydrolyzable nature.
Conventionally, stator cores are salvaged for recycling by stripping wire therefrom by one of two methods. In one method the wire is stripped from the stator core by simply pulling the wire from the core. In another method the stator is "burned" at about 400.degree. C. to 500.degree. C. for several hours to pyrolyze the wire enamel, varnish coatings and adhesives, slot liners, wedge and other insulation materials, and then the wire is pulled from the core. Neither method is entirely satisfactory, however, as the first method often results in broken wires which increases the difficulties attendant to their removal from the core, while the second method frequently causes deleterious changes in the electric characteristics of the stator core preventing its reuse. Also, some cores have residual oil or refrigerant which, when burned, degrade and result in even worse core degradation.
Wherefore, it is an object of this invention to provide an improved method for stripping stators. More specifically, it is an object of the present invention to provide a practical and economical process for stripping magnet wire from a stator core while substantially avoiding alteration of the electrical characteristics of the core so that the core can be salvaged for reuse. Another object of this invention is to provide a method for stripping magnet wire from a stator which requires less energy and less time than conventional "burning" techniques. Still another object of this invention is to provide a method of stripping magnet wire from a stator which avoids physical damage to the stator core.
These and other objects are achieved by the present invention wherein a stator comprising a core, magnet wire, and hydrolyzable insulation is contacted with steam under conditions of elevated temperature and pressure and for a time sufficiently great to cause degradation of said insulation but insufficient to cause deleterious side effects or damage to the stator core. Preferably, a stator is held in an environment of steam below the saturation pressure of the steam and at a temperature of from about 200.degree. to 350.degree. C. and an absolute pressure of from about 1,000 mm. to about 10,000 mm. Hg. After the insulation has degraded, the magnet wire is easily removed from the stator core as by pulling it or otherwise mechanically removing it therefrom.